The present invention relates to a container capable of heating the contents of the container, such as foods or beverages, for example, alcoholic beverages such as wine, sake, coffee, tea, soup, stew, dairy beverages, fruit juices and so on, from the inside and, in particular to a container free from the danger of bursting due to abnormal increase of the internal pressure of the reaction chamber upon violent progress of the heat generating reaction.
Self-heating containers are known, having a construction in which the container or cup for foods or beverages for example, and a heating means are assembled in a unit. This type of integrally heated container is so constructed that a reaction chamber is arranged within the container and two reaction components composed of an exothermic substance consisting of, for example, CaO and a reacting substance consisting of, for example, water are stored therein isolated from each other by a partition; and the heating is effected by operating a reaction initiation means consisting of, for example, a piercing spike which pierces said reaction chamber to rupture the partition, in order to cause contact of the reaction components with each other to initiate the exothermic hydration reaction. This internally heatable container has no means for guarding against an abnormal increase in the internal pressure of the reaction chamber. Thus the prior art internally heatable containers may burst upon initiating the heating reaction.